If the second round of the BMW Championships at Wentworth today had as much drama as the first it should be worth following - and that is referring only to Scotland's Marc Warren.

The 25-year-old winner of last year's Challenge Tour managed only a five-over-par 77 on his debut in the main tour's flagship event but it was eventful to say the least.

After a birdie at the third and eagle on the next, Warren was only two off the lead.

With seven to play he was still there, but things started to go wrong when he four-putted the long 12th for a triple-bogey eight.

Warren said: "I was walking to the next tee and they have astroturf covering concrete.

"However, I did not know there was concrete underneath.

"I whacked the turf with my putter and it was not until I reached the next tee I noticed my putter was upright, so I could not use it.

"I was just trying to take a bit of anger out but I should not have done it looking back."

He tried putting with "sand-wedge, wedge, three-wood, everything" but dropped six more shots in the next four holes - and then birdied the last two. Not that they were without incident. With his second shot to the 18th he hit a spectator!

Warren added: "As soon as I got round the corner there was a guy lying on the deck with blood pouring down the side of his face.

"Apparently my ball whacked him right on the top of the head.

"He was all right thankfully. I was speaking to him and he was fine.

"I needed to get my senses back after a crazy day. It feels like Sunday already the amount of things which have gone on out there."

Joint overnight leaders on 67 were English trio Luke Donald, Paul Casey and Nick Dougherty and South African Andrew McLardy.

Ernie Els, the man who has changed 17 of the 18 holes since last year, came in with a 69, while world number three Retief Goosen, the highest-ranked player in the field, was one further back.

Colin Montgomerie needs to improve on his opening 73 to avoid an eighth missed cut in his last 10 events and Lee Westwood (75), Darren Clarke (73) and Padraig Harrington (72) also need to find form to make it through.

Ashington's Kenneth Ferrie is two shots off the lead after an opening-round 69.